Auxiliary drive device for a wheelchair

ABSTRACT

An auxiliary drive device for a wheelchair has at least one freely pivotable electrically driven drive wheel and a coupling mechanism for coupling the auxiliary drive device to the wheelchair. The coupling mechanism includes a movable locking element which is movably supported in the coupling mechanism. The movable locking element can be in a locking position in which it causes locking in a positive-locking manner so that the auxiliary drive device is coupled to the wheelchair and, by operation of a handle, the locking element can be moved in a release position in which uncoupling of the auxiliary drive device from the wheelchair is possible.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U. S. Continuation Application of U.S. Pat.Application No. 16/553,377, filed Aug. 28, 2019, which claims priorityfrom German patent application No. DE 10 2018 122 360.9 filed on Sep.13, 2018, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

The technology relates to an auxiliary drive device for a wheelchair.

Wheelchairs basically can be grouped into two categories, namely on theone hand wheelchairs which primarily are designed for manual drive, thatis a drive provided by either the person sitting in the wheelchair, thisbeing done by hand, for instance via pushrims, which are mounted at thelarge rear wheels of the wheelchair, or by an assisting person pushingthe wheelchair, and, on the other hand, such wheelchairs which alreadyfrom their original concept are designed for electric drive.

Manually driven wheelchairs in general are characterized by aconsiderably lower weight as compared with those wheelchairs where anelectric drive unit is permanently installed. Furthermore, manuallydriven wheelchairs often are designed as so-called folding wheelchairswhich, not only due to their lower weight, but also due to the fact thatthey can be folded and therefore have smaller dimensions, can be easilytransported, for instance in the trunk of a passenger car.

Manually driven wheelchairs have, if the propulsion is effected by theperson sitting in the wheelchair, a therapeutic effect because providingthe driving power constitutes a valuable physical exercise. On the otherhand, when manually driving a wheelchair, wheelchair drivers doing sosometimes soon reach the limits of their physical capacities, especiallywhen slopes are to be negotiated, when the wheelchair has to bemaneuvered on difficult terrain or when long distances are to becovered. Furthermore, use of a manually driven wheelchair over a longtime may lead to injuries because of repeated high strain and topremature signs of wear in muscles, tendons and joints. For this reason,auxiliary drive devices for wheelchairs have been developed which, whenlater being attached to a wheelchair, support the user in moving thewheelchair.

Such an auxiliary drive device for a wheelchair can for instance beprovided by replacing the two original large rear wheels of thewheelchair by such rear wheels in which a hub motor is integrated. Suchan auxiliary drive device for a wheelchair is for instance disclosed inDE 197 48 201 C1.

US 2014/0262575 A1 discloses a different kind of auxiliary drive devicefor a wheelchair, namely a device which comprises an additional drivewheel which can be driven electrically, that is a drive wheel which isnot exchanged with an original wheel of the wheelchair but which is partof a separate device, which, in addition, comprises a coupling mechanismfor coupling the auxiliary drive device to the wheelchair.

A coupling mechanism for coupling such an auxiliary drive device to awheelchair must ensure safe and secure coupling. Furthermore, couplingand uncoupling should be easy to be accomplished and the coupling shouldbe preferably such that in order to negotiate obstacles like a curb,so-called tipping or tilting of the wheelchair for clearing thisobstacle, that is a lifting of the front wheels, should be possible.

SUMMARY OF THE INVENTION

It is desirable to provide an auxiliary drive device for a wheelchairwhich ensures safe and secure coupling where coupling and uncoupling canbe accomplished easily.

An aspect of the technology provides an auxiliary drive device for awheelchair which has at least one electrically driven drive wheel and acoupling mechanism for coupling the auxiliary drive device to thewheelchair. The coupling mechanism includes a locking element which ismovably supported in the coupling mechanism. The movable locking elementcan be in a locking position in which it causes locking in apositive-locking manner so that the auxiliary drive device is coupled tothe wheelchair. The locking element can be moved in a release positionby operation of a handle. In this release position, uncoupling of theauxiliary drive device from the wheelchair is possible.

The locking in a positive-locking manner ensures positive locking duringoperation. This positive, form-fit locking is ensured regardless ofwhich position the auxiliary drive device has with respect to thewheelchair to which it is coupled because the coupling is effected bythe movement of the locking element in the locking mechanism.Furthermore, coupling and uncoupling can be accomplished easily becausethe movably supported locking element can be moved into the releaseposition by operating the handle.

In one embodiment, this handle is designed and arranged such that it canbe used to carry the auxiliary drive device with one hand.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of the specification. The drawings illustrate exemplary embodimentsand, together with the specification, serve to explain principles anddetails of the disclosed technology.

FIG. 1 is a perspective view of a first embodiment of an auxiliary drivedevice for a wheelchair which is coupled to the axis of a wheelchair.

FIG. 2 is a side view of the auxiliary drive device according to FIG. 1wherein parts of the wheelchair are omitted in the depiction.

FIG. 3A is a perspective, partially cut-away view of a furtherembodiment of an auxiliary drive device for a wheelchair wherein thedrive wheel of the auxiliary drive device is in a position for drivingstraight forward.

FIG. 3B is a further perspective, partly cut-away view of the auxiliarydrive device according to FIG. 3A wherein the drive wheel of theauxiliary drive device is in a position for driving a curve in a stateof forward driving.

FIG. 4 is a back view of the auxiliary drive device according to FIGS.3A, 3B.

FIG. 5 is a partially cut-away side view of the auxiliary drive deviceaccording to FIG. 3 wherein the drive wheel of the auxiliary drivedevice is in a position for driving straight forward.

FIG. 6 is a view according to FIG. 5 with a coupled wheelchair beingdepicted only schematically wherein the drive wheel of the auxiliarydrive device is in a position for driving straight forward.

FIG. 7 is a schematic view according to FIG. 6 wherein the drive wheelof the auxiliary drive device is in a positon for driving straightbackwards.

FIG. 8 is a view of the auxiliary drive device according to FIG. 3 takenfrom below wherein the drive wheel of the auxiliary drive device is in aposition for driving a curve in a backwards direction.

FIG. 9 is a top view of the auxiliary drive device according to FIG. 3wherein lateral elements of the frame of the wheelchair coupled to itare shown only schematically and the drive wheel of the auxiliary drivedevice is in a position for driving a curve in the forward direction.

FIG. 10 is a partially cut-away perspective view of a further embodimentof an auxiliary drive device for a wheelchair.

FIG. 11 is a view of a detail of an embodiment of an auxiliary drivedevice for a wheelchair where the drive wheel is in a first stopposition.

FIG. 12 is a view of a detail of the embodiment of the auxiliary drivedevice according to FIG. 11 where the drive wheel is in a second stopposition.

FIG. 13 is a perspective front view of an embodiment of an operatingsatellite.

FIG. 14 is a perspective rear view of the operating satellite accordingto FIG. 13 .

FIG. 15 is a partial view of the operating satellite according to FIG.13 in a first rotational position.

FIG. 16 is a partial view of the operating satellite according to FIG.13 in a second rotational position.

FIG. 17 is a partial rear view of the operating satellite according toFIG. 13 where a cover element has been removed.

FIG. 18 is an exploded view of the operating satellite according to FIG.13 having an operating satellite-wheelchair mounting element and anoperating satellite locking element.

FIG. 19 is a view of an operating satellite mounting surface of theoperating satellite locking element according to FIG. 18 .

FIG. 20 is a combined depiction of the operating satellite according toFIG. 13 having the operating satellite wheelchair mounting element andthe operating satellite locking element.

FIG. 21 is an exploded view of a reversing mechanism of an operatingsatellite mounting tilting element.

FIG. 22 is a schematic view of a released position of latches of anoperating satellite mounting tilting element.

FIG. 23 is a schematic view of a latch position of latches of anoperating satellite mounting tilting element.

FIG. 24 is a side view of a coupling mechanism of an embodiment of anauxiliary drive device for a wheelchair together with a wheelchaircoupling element in a ready to be coupled position.

FIG. 25 is a side view of the coupling mechanism according to FIG. 24 ina locked position.

FIG. 26 is a side view of the coupling mechanism according to FIGS. 24and 25 in a release positon.

FIG. 27 is an exploded perspective view of the coupling mechanismaccording to FIGS. 24 to 26 .

FIG. 28 is a rear view of the coupling mechanism according to FIGS. 24to 27 .

FIG. 29 is a depiction of a display of a smartphone arranged foradjusting the sensitivity of a rotational control ring.

FIG. 30 is a depiction of a display of a smartphone arranged for settingan automatic adaption of the travelling speed when negotiating a curvein dependence of the steering angle of the drive wheel.

DETAILED DESCRIPTION OF THE INVENTION

In the following, some embodiments of the technology are described withreference to the accompanying drawings. Note that the followingdescription is directed to illustrative examples of the technology andnot to be construed as limiting the technology. Factors including,without limitation, numerical values, shapes, materials, components,positions of the components, and how the components are coupled to eachother are illustrative only and not to be construed as limiting thetechnology. Further, elements in the following example embodiments whichare not recited in most generic independent claims of the technology areoptional and may be provided on an as-needed basis. The drawings areschematic and are not intended to be drawn to scale. Throughout thepresent specification of the drawings, elements having substantially thesame function and configuration are denoted with the same numerals toavoid any redundant description.

FIG. 1 shows a perspective view of an embodiment of an auxiliary drivedevice 100 for a wheelchair which is coupled to an axis 501 of awheelchair 500. In the embodiment as depicted, the axis 501 is the axisconnecting the two large rear wheels 502, i.e. the left rear wheel 502L,as seen in the forward driving direction, and the right rear wheel 502R,as seen in the forward driving direction. As common in case of manuallydriven wheelchairs, pushrims 504 are mounted at both large rear wheels502L, 502R. Via said pushrims 504, the wheelchair can be manuallypropelled and steered. Furthermore, the wheelchair 500 has two small andfreely pivotable front wheels 505. FIG. 2 shows the embodiment of theauxiliary drive device 100 according to FIG. 1 in a side view whereinparts of the wheelchair 500, especially the right rear wheel 502R, areomitted in this depiction.

The auxiliary drive device 100 serves to be used as an auxiliary drivedevice for a wheelchair 500 which basically is intended to be manuallydriven. Details regarding the function of the auxiliary drive device 100as well as the coupling to the wheelchair 500 and the structure of therespective coupling mechanism 300 are explained in detail further below.

General Structure of the Auxiliary Drive Device 100

FIG. 3A is a perspective view of the auxiliary drive device 100 whereinthe drive wheel 110 of the auxiliary drive device 100 is in a positionfor driving straight forward. FIG. 3B shows the auxiliary drive device100 according to FIG. 3 in an operational condition in which the drivewheel 110 is in a position for driving a curve in a forward direction.FIG. 4 is a rear view of the auxiliary drive device 100 and FIG. 5 is apartially cut-away side view of the auxiliary drive device 100.

Main components of the auxiliary drive device 100 are inter alia a drivewheel 110, an auxiliary drive device main body 120 and a couplingmechanism 300. An operating satellite 200 is provided for controllingthe auxiliary drive device 100 and its functions by a user.

The drive motor of the drive wheel 110 is an electric hub motor 111, forexample a brushless DC motor with or without a gearing mechanism, whichis integrated in the drive wheel 110. The tire surface 112 of the drivewheel 110 naturally is subject to wear. It is therefore an advantage ifthe tire can be replaced easily. In case of the embodiment as shown inthe figures, the tire surface is split in the center, connected to therotating part of the drive motor in a positive-locking manner and fixedfrom the side via tire surface bolts 113. It is noted that there areseveral other technical options for different kinds of connections, forexample force-fitting connections like adhesion, which a person skilledin the art is aware of.

The electric hub motor 111 is connected via an electric conductor to amain power storage in the form of a rechargeable main battery 121located in the auxiliary drive device main body 120. Further elementsnot shown in the figures are also located in the auxiliary drive devicemain body 120, for instance elements of a battery management system formanaging the state of charge, particularly the charging and dischargingof the main battery 121, elements of a power and control unit, i.e. anelectronic control device for controlling the functions of the auxiliarydrive device 100, particularly the electric hub motor 111, as well asfurther electric components of the auxiliary drive device 100, forexample a rear light 122, which for instance can be provided in the formof a band of LED lighting elements glued to said band, which can besupplied with power from the rechargeable main battery 121. At asuitable position of the auxiliary drive device main body 120, there canalso be provided a main switch 123 for switching the auxiliary drivedevice 100 to an OFF-state and a ready-to-operate state as well as amain body charging socket 124, for example in the form of a USB socket,which is connected in particular to the rechargeable main battery 121.

The power and electronic control unit is also connected to the operatingsatellite 200 which, as well as its functions and the sensors usedtherefore, will be explained in more detail further below.

FIGS. 1 and 2 show the coupling of the auxiliary drive device 100 at theaxis 501 of the wheelchair 500 which allows a pivotional movement of theauxiliary drive device 100 in a plane which is vertical to the axis 501but not a pivotional movement in a plane in which the axis 501 lies,i.e. which the axis 501 is part of. Accordingly, the drive wheel 110 hasto allow a steering operation if lateral slip of the drive wheel 110 isto be avoided when the wheelchair negotiates a curve. In case of anauxiliary drive device as disclosed in US 2014/0262575 A1, suchdrivability of the drive wheel which is arranged in a rigid manner withrespect to the wheelchair is provided by lateral rollers arranged alongthe circumference of the drive wheel.

In case of the embodiment of an auxiliary drive device 100 according tothe present technology as shown in the figures and as described here, acompletely different technical solution is chosen. The drive wheel 110of the auxiliary drive device 100 is freely pivotable, which means, thatits running direction with respect to the wheelchair 500 isself-adjusting when the auxiliary drive device 100 is coupled to thewheelchair 500. In order to provide this function, a steering shaft 130is provided to which the drive wheel 110 is connected. In oneembodiment, the drive wheel 110 is supported in a steering fork 131which is fixedly attached to the steering shaft 130. It has to be notedthat a person skilled in the art is aware of various different technicalmeans to connect the drive wheel 110 to the steering shaft 130.

The steering shaft 130 is rotatably supported in the auxiliary drivedevice main body 120 and specifically in such a manner that it can berotated without hindrance over a wide range of rotation. In anadvantageous embodiment, the steering shaft 130 can be rotated withoutany hindrance over a range of rotation of at least 360°, in a specificembodiment over a range of rotation of for instance 380°. In otherwords, the steering fork 131 and, together with it, the drive wheel 110supported therein, can be freely pivoted with respect to the auxiliarydrive device main body 120 and, when the auxiliary drive device 100 iscoupled to a wheelchair 500, also with respect to the wheelchair 500.

In one embodiment, the auxiliary drive device main body 120 is coupledto the wheelchair 500 for operation of the auxiliary drive device 100such that the steering shaft 130 and the drive wheel 110, when thelatter is in a position for driving straight forward, lie in a planewhich is in the center between the two rear wheels 502R, 502L.

In one embodiment, the steering shaft 130 is, when the auxiliary drivedevice 100 is coupled to the wheelchair 500 in a state ready to beoperated, in a position which ideally is perpendicular to the groundsurface on which the wheelchair 500 stands. In other words, when thewheelchair 500 stands on a flat and horizontal surface, the steeringshaft 130 stands perpendicular to this flat and horizontal surface, i.e.vertically (see FIG. 6 ), when the auxiliary drive device 100 is coupledto the wheelchair 500 ready to be operated.

Preferably, the deviation from this ideal case concerning the verticalposition should not be larger than 5°, in a specifically preferredembodiment it should not be larger than 3°.

A further geometric feature of the embodiment according to FIG. 6 isthat an imaginary line extending through the axis of rotation of thedrive wheel 110 and the axial center of the steering shaft 130 isinclined with respect to the steering shaft 130, i.e. the center axis ofthe steering shaft 130 in an angle of about 25°, and that in a preferredembodiment this angle is not deviated from by more than 5°, in aspecifically preferred embodiment not more than 3°, and that a castor isprovided, which means that the distance from a vertical line extendingthrough the axis of rotation of the drive wheel 110 to the horizontalcontact surface of the wheelchair 500 to the steering shaft 130, i.e.the center line of the steering shaft 130, is for example 60 millimeterand that in a preferred embodiment the deviation from this value is notmore than 20 millimeter, in a specifically preferred embodiment not morethan 10 millimeter. Furthermore, in the embodiment as described here,the contact point of the drive wheel 110 with the ground surface is, ineach rotational position of the steering shaft 130, behind the contactpoint of the rear wheels 502R, 502L, if seen in a forward drivingdirection of the wheelchair 500.

Although the drive wheel 110 is freely pivotable due to the freelypivotable steering shaft 130, in operation, that is when the auxiliarydrive device 100, powered by the electric hub motor 111, propels thewheelchair 500 to which the auxiliary drive device 100 is connected,said drive wheel 110, in a self-acting manner, takes a position whichallows a steering of the wheelchair by the user via the pushrims 504without any problems. The drive wheel 110 automatically aligns itself inthe direction of the curve which is defined by respective manual actionvia the pushrims 504 of the two rear wheels 502R, 502L. This includesdriving on a straight both in forward and backward direction, drivingcurves of any radius and even turning the wheelchair on the spot.

It is to be noted that auxiliary drive devices of the present kinds haveto be suited to be mounted to a variety of wheelchairs. On the otherhand, wheelchairs are designed in accordance with the physicaldimensions of the user. This leads to the fact that inter alia theseating height of the wheelchairs and particularly the diameter of therear wheels 502R, 502L vary. Accordingly, also the height of an axle barconnecting the rear wheels 502R, 502L varies. Typical wheelchairscommercially available have usually rear wheels with a diameter of forinstance 22″, 24″, 25″ or 26″. In accordance with this customaryincrements, various variants of the steering fork 131 can be providedfor adapting the auxiliary drive device 100 to the dimensions of a givenwheelchair, specifically with respect to the geometrical aspects asexplained above. Since in many cases medical aids are used in aplurality of applications and auxiliary drive devices of the presentkind during their life cycle may be mounted to various wheelchairs, easyreplacement of respective components to be adapted constitute animportant economic factor.

Steering Motion and Power Supply

As explained above, it is advantageous if the drive wheel 110 can assumeany pivotable position which means that the steering shaft 130 canfreely rotate, preferably over 360°. However, this basically includesthe possibility that the steering shaft 130 rotates several subsequenttimes in the same direction of rotation.

As also explained above, the electric hub motor 111 is connected via anelectrical conductor to the rechargeable main battery 121 which isarranged in the auxiliary drive device main body 120. If this electricalconductor is provided by a cable, care has to be taken that a pluralityof rotations of the steering shaft 130 in the same direction does notlead to a winding of the cable which finally would hinder therotatability of the steering shaft and, accordingly, would interferewith the operability of the auxiliary drive device 100.

In one embodiment, power transmission can be provided via a slip ring118 in a position where a rotating component and a fixed component haveto be bridged. Such an embodiment is shown in FIG. 10 .

Another embodiment includes a stop for the rotation of the steeringshaft 130 which allows preferably more than a rotation over 360°,however prevents a plurality of sequential full rotations in one and thesame direction. Such an embodiment is shown in FIGS. 11 and 12 . A stopgliding element - guiding element 132 which is fixedly connected to thesteering shaft 130 has a crescent-shaped elongated hole 133 in which astop gliding element 134 is movably guided. When the steering shaft 130is rotated in a first direction of rotation (see FIG. 11 ), the stopgliding element 134 gets in abutment of a first side 135A of a stopelement 135 which is fixedly arranged with respect to the auxiliarydrive device main body 120, wherein it rests against a first end of theelongated hole 133. When the steering shaft 130 is rotated in adirection opposite to the first direction of rotation (see FIG. 12 ),the stop gliding element 134 gets in contact with a second side 135B ofthe stop element 135, wherein it rests against a second end of theelongated hole 133.

Due to the movability of the stop gliding element 134 in the elongatedhole 133, with appropriate choice of the dimensions of the respectivecomponents, it can be achieved that the steering shaft 130 can berotated over a range of for instance 380° before it gets in abutment.

This makes it possible that the drive wheel 110 can be pivoted by morethan 360° and, therefore, can assume all directions which preferably aredesired for a driving operation and, on the other hand, it is stillavoided that the steering shaft 130 rotates several times subsequentlyin the same direction so that winding of a power cable which connectsthe drive motor 111 to the rechargeable main battery 121 in theauxiliary drive device main body 120 is prevented.

Motion-Based System and Operating Satellite

In one embodiment, the auxiliary drive device 100 can be operated as apurely motion-based system, i.e. a system in which a motion,specifically of the drive wheel 110, is detected and this motion then issupported or amplified, respectively, by the electric motor. If, forinstance, the wheelchair 500 to which the auxiliary drive device 100 iscoupled to, is manually propelled by the user via the pushrims 504 atthe rear wheels 502R, 502L in a direction for driving forward, the powerand the electronic control unit for controlling the functions of theauxiliary drive device 100 detects this motion via respective sensors,which include, without limitation, one or more of the following sensors,namely a rotational speed sensor, which detects the rotational speed andthe direction of rotation of the drive wheel 110, and/or one or moreacceleration sensors which detect acceleration in various spatialdirections, a gyro sensor and further optical, capacitive or inductivesensors, as the case shall be also a steering shaft rotational anglesensor 105 (see FIG. 3B) which detects the position of the steeringshaft 130, and controls the hub motor 111 in order to provideelectromotive rotation in the detected direction.

In another embodiment, operation is effected via an operating satellite200 to be operated by the user. It is to be noted that this embodimentalso can have one or more of the sensors as listed above which can beused in addition or alternatively also for other functions. Thestructure of this embodiment is explained in the following. Adescription of the operating functions and the drive followssubsequently.

An embodiment of the operating satellite 200 is shown in FIGS. 13 to 20. One of various positions where the operating satellite 200 can beattached to a wheelchair 500, preferably in a removable manner, as shownin FIG. 2 .

FIGS. 13 and 14 show, each in a perspective view, a front view and arear view of an embodiment of an operating satellite 200. The operatingsatellite 200 serves for controlling the auxiliary drive device 100 andhas, specifically inside of it, the electric and electronic componentsnecessary for this purpose (not shown in the figures) which for thefurther description of this embodiment in the following are summarizedunder the term operating satellite control unit. Bidirectionalcommunication between the operating satellite control unit of theoperating satellite and the electronic control unit for controlling thefunctions of the auxiliary drive device 100 can, for instance, beprovided via wires and cables, not shown in the figures, or wireless,for instance by a Bluetooth coupling.

The operating satellite 200 has an operating satellite control portion202 and an operating satellite mounting element 210.

The operating satellite mounting element 210 serves for mounting theoperating satellite 200 to a wheelchair 500. For this purpose, a quickrelease unit can be latched with an operating satellite mounting pivotelement 220 by hooking an undercut 201 of the operating satellitemounting element 210 in a fixing hook 222 of the operating satellitemounting pivot element 220. Then, the operating satellite mountingelement 210 is brought in abutment with the operating satellite mountingpivot element 220 so that a locking hook 211 provided at the operatingsatellite mounting element 210 snaps into place with spring-loadedlatches 221 at the operating satellite mounting pivot element 220 (see,also with respect to respective start up slopes, FIGS. 18 to 20 ).Releasing the operating satellite mounting element 210 from theoperating satellite mounting pivot element 220 is done in a reversesequence wherein the spring-loaded latches 221 of the operatingsatellite mounting pivot element 220 can be retracted (i.e. lowereddown), by means of a release button 223 which is also spring-loaded andwhich is connected to the spring-loaded latches 221 of the operatingsatellite mounting pivot element 220 via a reverse mechanism.

As shown in FIGS. 21 to 23 , the two latches 221 at the upper ends ofrespective latch bars 221A are pushed each via a respective pressurespring 225 in the latch position as shown in FIG. 23 and are connectedvia reverse levers 226 to a push rod 224 which in turn is connected to arelease button 223. If, starting out from the latch position as shown inFIG. 23 , the release button 223 is pushed against the spring force ofthe pressure springs 225 in the direction towards the housing of theoperating satellite mounting pivot element 220, the latch bars 221A areshifted due to the reverse levers 226 in the opposite direction of thepush rod 224 and cause a lowering of the latches 221 so that theoperating satellite mounting pivot element 220 is released. Thiscondition of a release positon of the latches 221 is shown in FIG. 22 .If the release button 223 is released, the latches 221 return, due tothe pressure force of the pressure springs 225, back into their latchpositons according to FIG. 23 .

The operating satellite mounting pivot element 220 can be connected to awheelchair mounting element 230 in a rotational positon which can befreely determined and can be fixed by a mounting bolt 231 in this freelydeterminable position. Due to the structure as described above and shownin the figures, there is a great variety of possible positions forattaching the operating satellite 200 to a wheelchair 500 and forchoosing appropriate positions for such attachment. In particular, it ispossible to select either the right side or the left side of thewheelchair for such attachment which allows easy operation forleft-handed persons and right-handed persons, respectively.

The operating satellite control portion 202 has control and switchingelements by which via respective actuation processes the control anddrive of the auxiliary drive device 100 can be effected. Specifically,these processes can be effected via a rotational control ring 203 whichis arranged at the outer circumference of the operating satellitecontrol portion 202 and provided with grip links 208 and a push controlknob 204 within the outer circumference of the operating satellitecontrol portion 202 and, thus, also within the outer circumference ofthe rotational control ring 203. The push control knob 204 can be pushedin the direction of the axis of rotation of the rotational control ring203 and is designed having a considerable surface and is attached uponmounting at the wheelchair with the face surface of the operatingsatellite control portion 202 facing to the outside of the wheelchair(not facing to the center of the wheelchair) and therefore also at theouter part of the push control knob 204.

The rotational control ring 203 can be rotated in both directions of thecircumference, that is clockwise and counter clockwise, with no limit.No respective abutment is provided. However, the rotational control ring203 is provided with a clearly sensible ratchet which provides the userupon rotating this element with a tactile and/or audible operationfeedback, thus providing distinctive increments of rotation. In otherwords, the rotational control ring 203 can be rotated arbitrarily far,over as many full rotations as desired, and in each direction. However,the angle range of 360° of a full rotation is divided in a certainnumber of sub-ranges, namely the above-mentioned increments provided bythe ratchets, so that each time when such a sub range is exceeded, arespective ratchet is sensible and/or audible.

Exceeding such a sub range or increment triggers a signal of theoperating satellite control unit which signal can be defined in aprogram with respect to its characteristics and is transmitted to theelectronic control unit for controlling the functions of the auxiliarydrive device 100, wherein also the direction of rotation of theoperation influences the content of the signal.

Details concerning the control functions which are transmitted to theelectronic control unit for controlling the functions of the auxiliarydrive device 100 by operating the operating satellite 200 are explainedfurther below.

The push control knob 204 can be operated by pressing it in an inwarddirection against pressure force of a spring. Its operation alsotriggers a signal of the operating satellite control unit which istransmitted to the electronic control unit for controlling functions ofthe auxiliary drive device 100 wherein also the duration of theoperation has influence on the content of the signals.

On the outer side of the operating satellite 200, in case of the shownembodiment on the outer circumference of the operating satellite controlportion 202, there is provided a display device 205, for instance in theform of LED displays. This display device 205 displays informationregarding operational conditions of the drive device or the auxiliarydrive device 100, respectively, and informs, for example, in the shownembodiment regarding the state of charge of the main battery 121 in theauxiliary drive device main body 120, for instance by providing a stripof several white LED elements 205A wherein the number of luminous orlighted elements corresponds to the state of charge, and also concerningthe state of charge of a rechargeable operating satellite battery (notshown) which is integrated in the operating satellite, for instance by asingle RGB LED element 205B which communicates the state of charge bychanging the color.

The display device 205 is designed such that its arrangement on theoperating satellite can be adjusted, that is, it can be altered. Thismakes it possible to adjust the positon of the display device 205 withrespect to its visibility for a person sitting in the wheelchair 500 inconnection with a respective place of attachment of the operatingsatellite 200 at the wheelchair 500. In the embodiment as shown in thefigures, this is for instance achieved by the structure as describedbelow.

A cover element 206 is provided at a face side of the operatingsatellite control portion 202 which, when mounted at a wheelchair 500,faces to the center of the wheelchair 500. This cover element 206 can beremoved and also be fixed back in place by operating a spring-loadedunlocking element 209 (see FIG. 14 and FIG. 17 ). Removing the coverelement 206 allows access to three fixing screws 207, to an adaptorcharging socket 218 arranged at the operating satellite 200, forinstance in the form of a USB socket, and to a pairing button 219.

Untightening the three fixing screws 207 allows rotating the outercircumference of the operating satellite control portion element 202 ina circumferential direction (see FIG. 15 and FIG. 16 ). The subsequenttightening of the three fixing screws 207 fixes the outer circumferenceof the operating satellite control portion 202 in the newly selectedposition with respect to the operating satellite mounting element 210.Hereby it can be ensured that, regardless at which part of thewheelchair 500 and in which position with respect to the wheelchair 500the operating satellite 200 is attached, the display device 205 isalways within sight of the user.

The adaptor charging socket 218 can be used for charging the operatingsatellite battery of the operating satellite 200 also upon operation,that is when the wheelchair travels supported by the auxiliary drivedevice 100, wherein the energy for this purpose can either be providedby a separate power source or by connection with the main body chargingsocket 124 provided at the auxiliary drive device main body 120.

The pairing button 219 serves to establish a Bluetooth connection withthe electronic control unit in the auxiliary drive device main body 120for controlling the functions of the auxiliary drive device 100.

Operating Function and Travel

In the following, as an example, operation of the auxiliary drive device100 and the drive or travel of a wheelchair 500 connected to such anauxiliary drive device 100 are explained. It is understood that aplurality of amendments from this exemplary embodiment can be providedby a person skilled in the art.

Starting out from a nonoperating state, in which the auxiliary drivedevice 100 is switched OFF, the auxiliary drive device 100 is put into aready to operate state by operating the main switch 123 at the auxiliarydevice main body 120. In the ready to operate state, the electroniccontrol unit in the auxiliary device main body 120 for controlling thefunctions of the auxiliary drive device 100 receives signals from theoperating satellite control unit provided in the operating satellite200.

When in this ready to operate state of the auxiliary drive device 100the push control knob 204 at the operating satellite control portion 202of the operating satellite 200 is pushed for longer than a respectivethreshold value, which for instance can be 3 seconds, the auxiliarydrive device 100 is put into a ready to drive state. If in this ready todrive state the rotational control ring 203 at the operating satellitecontrol portion 202 of the operating satellite 200 is rotated in a firstdirection, for instance in, as seen from a user sitting in thewheelchair, a forward direction, the electronic control unit forcontrolling the functions of the auxiliary drive device 100 receivescorresponding signals from the operating satellite control unit anddrives the motor 111 such that a torque is delivered for rotating thedrive wheel 110.

Turning of this control element, namely of the rotational control ring203, is a direction sensitive operational process which causes,depending on the operational direction, an activation of the auxiliarydrive device 100 corresponding to this operational direction wherein thecorrelation between the operational direction of the rotational controlring 203 and the activation of the auxiliary drive device 100 caused bythis rotation can be changed.

For instance, the rotational direction of the rotational control ring203 which initiates start of a drive can be changed, for instance byrespective programming. This means that regardless of whether theoperating satellite 200 is mounted on the left side or on the right sideof the wheelchair 500, which for instance can be chosen depending onwhether the user is left-handed or right-handed, the start of a drivealways can be initiated by rotation in a forward direction which allowsan intuitive operation. Such programming, just as also other options forprogramming which can be made by a user, can be done with the aid of anend terminal like for instance a PC or a smartphone where a respectivesoftware designed to run on a mobile device, in the following referredto as app, has been downloaded on, i.e. a respective user program whichis provided to the user.

The level of the torque is set such that a respective travelling speedis achieved. The level of the travelling speed depends on how manyratchets (increments) have been exceeded when the rotational controlring 203 is rotated.

In other words, after switching ON into the ready to operate state bypushing the main switch 123 and switching ON to the ready to drive stateby continued pushing of the push control knob 204, the user can startdriving with electric power of the auxiliary drive device 100 byrotating the rotational control ring 203 in a forward direction. Thespeed of the drive is set by the user such that a certain number ofratchets (increments) are exceeded upon rotating the rotational controlring 203. In other words, if for instance, starting out from a standstill condition, the rotational control ring 203 is rotated such thatfive ratchets are exceeded, a predetermined speed will be reached. If inthe same rotational direction another ratchet is exceeded, the speedwill be increased by a predetermined amount. On the other hand, if therotational control ring 203 will be rotated in an opposite direction,each time a ratchet is exceeded, the speed will be lowered to a lower bya predetermined amount.

The correlation between ratchet and speed is freely programmable whereinonly an upper speed limit can be provided which cannot be changed by theuser. The correlation between ratchet and speed is expressed in how manyratchets have to be exceeded in order to obtain a specific speed, namelyan increase of the speed or a reduction of the speed. This adjustabilitymakes it possible to change the response or sensitivity, respectively,of the rotational control ring 203 and thus adapt it to specific needsof various user groups and their level of handicap. This is a particularadvantage for those users who have limited coordination ability becausethe adjustment movement then, as the case may be, can be executed moreheavy-handed, that is in a kind of gross motor manner.

In one exemplary embodiment, the setting can be such that the upperspeed limit is set to 12 km/h and the correlation between ratchet andspeed is set such that exceeding one ratchet means a speed increase of 1km/h. If, under such a condition, a user, starting from a standing stillcondition, rotates the rotational control ring 203 by one ratchet in aforward direction, the wheelchair 500 starts moving due to the electricdrive power of the auxiliary drive device 100 with a driving speed of 1km/h. Each further rotation of the rotational control ring 203 in aforward direction exceeding one further ratchet increases the drivespeed by 1 km/h. In another exemplary embodiment, the setting forinstance could be that each time a ratchet is exceeded the change inspeed is only 0.5 km/h. If the set top speed is reached, which meansthat in the first example given above 12 ratchets are exceeded and inthe second example 24 ratchets are exceeded, further rotation of therotational control ring 203 in the forward direction is possible as faras the mechanics are concerned. However, it has no effect as far ascontrol of the auxiliary drive device is concerned.

Turning the rotational control ring 203 in a backward directiondecreases the speed in a corresponding manner, namely with a set speedincrement each time a ratchet is exceeded. Turning the rotationalcontrol ring 203 in a backward direction therefore leads to a reductionin speed and, after a respective number of ratchets have been exceeded,it leads to complete stopping, that is to termination of the productionof drive torque. Also, in this case it is possible to further rotate therotational control ring 203 in a backward direction as far as themechanics are concerned, however without any effect concerning controlfunctions.

A complete stop is also possible by pushing the push control knob 204during the drive. In this case, a short push is sufficient. This pushingof the push control knob 204, even if it is only for a short period oftime, makes it possible to immediately terminate the production of drivetorque.

If in the ready to drive condition of the auxiliary drive device 100 thepush control knob 204 at the operating satellite control portion 202 ofthe operating satellite 200 is pushed for a longer duration than arespective threshold value, which threshold value for instance can be 3seconds, the auxiliary drive device 100 is set back into the ready tooperate state.

The above describes basic aspects of the operation of the auxiliarydrive device 100 by means of respective electric and electroniccomponents like switches, control elements and programming. In thefollowing, operation and drive with a wheelchair 500 at which anembodiment of the auxiliary drive device 100 is coupled to is described.

As explained above, the drive wheel 110 is supported via the steeringshaft 130 and can be freely pivoted with respect to the auxiliary drivedevice main body 120. Force is developed by the auxiliary drive device100 basically only with respect to propulsion, i.e. with respect to therotation of the drive wheel 110 by the hub motor 111. Steering iseffected via the pushrims 504 at the rear wheels 502R, 502L such thatwhen driving a curve is intended, by decelerating the inner rear wheel,i.e. the inside rear wheel of the intended curve. The freely pivotabledrive wheel 110 then behaves with respect to its pivoting, in spite ofthe applied drive power, like a freely pivotable castor and alignsitself automatically corresponding to the curve.

The freely pivotable drive wheel 110 provides, especially as comparedwith a drive wheel which is rigidly installed with respect to thedriving direction, superior maneuverability and allows simple initiationof driving a curve without the need of substantial force. Since thedrive wheel 110 always by itself takes the position of the vector ofthis curve which is initiated manually via the pushrims 504 by one-sideddeceleration, negotiating the curve is initiated easily also when poweris provided from the auxiliary drive device 100. If one rear wheel ofthe wheelchair is completely stopped, this leads to turning on the spot.Furthermore, driving in a backward direction is possible in a positon ofthe drive wheel which is opposite to the one for driving in a forwarddirection. The physical conditions which specifically include the freelypivotable drive wheel and the castor and, preferably, the coupling inthe center, and the application of the power of the drive wheel 110rearwards of the contact point of the large wheelchair wheels 502R, 502Lprovide responsive and agile handling and driving performance withlittle effort as far as manual forces are concerned.

Due to the fact that steering is effected via the pushrims 504 at therear wheels 502R, 502L, attachment of the operating satellite ispreferably done at a positon which the hand of a user lying at thepushrim 504 can reach quickly and intuitively.

For all settings which can be done by a user it is possible, asexplained above, to provide the option of a computer program installedon an end terminal, for instance a smartphone app or a PC serviceapplication. This does not only relate to the functional steps describedabove like the operation sensitivity of the rotational control ring 203.Also switching ON and switching OFF can be done by a user by means of asmartphone and a respective user application. If, for instance duringtraveling on public roads, it should be getting dark and switching ON ofthe rear light 122 should become necessary and a switch for switching ONthe rear light 122 at the auxiliary drive device main body 120 should bedifficult to be reached by a user or could not be reached at all, theuser can switch ON the rear light easily while sitting in the wheelchair500 by means a respective smartphone app. Carrying along a separatebattery light for such cases is therefore not necessary.

Cornering Speed Limitation

In one embodiment of an auxiliary drive device propelling a wheelchairby electric power in the way described above, it is possible to reducethe cornering speed when a curve is negotiated.

Reducing the drive power especially in narrow curves can improve thecontrollability of the wheelchair, especially for wheelchair drivershaving a higher spinal paralysis and limited function of the hand andfingers so that controlling the wheelchair under demanding driveconditions can be difficult. Particularly for such user groups, limitingthe cornering speed or providing automatic reduction of the corneringspeed can be a contribution to enhanced safety.

Appropriate reduction of the drive power, i.e. the driving torque of themotor 111 of the drive wheel 110, also can be useful during drive innarrow environments like indoors where hitting furniture and otherobjects must be avoided or in heavily frequented pedestrian zones.Generally, in narrow curves an appropriate reduction of the corneringspeed can be an additional safety feature.

For realizing such cornering speed limitation, at least one sensor isprovided which serves to detect cornering and/or the cornering speed. Inone embodiment, the electronic control unit for controlling thefunctions of the auxiliary drive device 100 uses a plurality ofrespective sensors including, but not limited thereto, a steering shaftrotational angle sensor 105 (see FIG. 3B) which detects the positon ofthe steering shaft 130, a rotational speed sensor detecting therotational speed and the direction of rotation of the drive wheel 110,several acceleration sensors detecting accelerations in various spatialdirections, a gyro sensor as well as optical, capacitive and/orinductive sensors, based on signals from one or more of these sensors,the hub motor 111 is driven such that electro motor drive torque isproduced only in a manner which is suitable for the present drivingsituation.

A drive torque leading to a constant drive straight ahead for instancecan be reduced depending on the detected radius of the curve wherein thereduction increases when the radius of the curve becomes smaller and/orthe cornering speed increases.

Respective values can be stored in maps and the values can be determinedin respective experiments. A control program stored in the electroniccontrol unit for controlling the functions of the auxiliary drive device100 then can, based on current sensor signals, refer to such map whenconducting respective calculations. Alternatively, the control programcan execute real-time calculation on the basis of respective signalsfrom the sensors.

If for instance the steering shaft rotational angle sensor 105 whichdetects the positon of the steering shaft 130 is, in addition tomonitoring the driving speed, used as one of the main input values forthe function of the cornering speed limitation, this sensor canpermanently monitor the steering angle of the drive wheel 110.

Furthermore, settings can be made via a computer program or an externalinterface defining by which amount the drive power or the drive torque,respectively, shall be reduced depending on the radius of the curve orthe steering angle. Moreover, in cases where the radius of the curveincreases again and/or transition is made to driving straight ahead, thedrive power or drive torque, respectively, can be increasedautomatically.

Coupling Mechanism (Structure)

The coupling of the auxiliary drive device 100 to the wheelchair 500 hasto be safe and secure. Furthermore, coupling and uncoupling should beeasy to be accomplished and the coupling should be preferably such thatin order to negotiate obstacles like a curb, so-called tipping ortilting of the wheelchair for clearing this obstacle, that is a liftingof the front wheels, should be possible. One embodiment having acoupling mechanism 300 described below with reference to FIGS. 24 to 28, fulfils all these requirements.

The coupling mechanism 300 according to FIGS. 24 to 28 is shown as astructural unit having a coupling mechanism main body 320 in whichcoupling grooves 321 are formed, which coupling mechanism main body 320serves for supporting functional elements of the coupling mechanism 300,specifically a handle 310 and a rocker 311 connected thereto, and whichcoupling mechanism main body 320 can be mounted to the front end of theauxiliary drive device main body 120.

It is to be noted that in a further embodiment the functions of thecoupling mechanism main body 320 can be realized by respective elementsformed in the same manner which elements according to this embodimentare part of the auxiliary drive device main body 120. In other words, itis possible to design the coupling mechanism main body 320 and theauxiliary drive device main body 120 as an integrated unit.

The coupling grooves 321 are formed basically V-shaped in order tofacilitate insertion of a coupling pin 381 which is preferably formedcylindrical. The coupling pin 381 is an embodiment of an element to beheld in a positive-locking manner in order to effect the coupling. It isunderstood that such an element to be kept in a positive-locking mannerin order to effect the coupling can also have different shapes and canbe formed in a different way. The coupling pin 381 described inconnection with the present embodiment can be formed in two parts andcan be attached at both sides of a coupling clamp 380 which can beattached removably at an axis 501 of a wheelchair 500 (see FIG. 1 andFIG. 2 ). In case a wheelchair does not have such an axis, acorresponding component (not shown) which fulfils the supportingfunction of the axis for such coupling clamp 380 can also be provided asa separate component and attached to the wheelchair, for instance byrespective bolts.

The rocker 311 is firmly and rigidly connected to the handle 310 andsupported via a rocker support pin 312 in the coupling mechanism mainbody 320 such that it can be rotated over a certain angular range aroundthe center axis of the rocker support pin 312 and in particular canassume positions between a locked operational position shown in FIG. 25and a release position shown in FIG. 26 with a ready to be coupledposition in between and shown in FIG. 24 .

Bores 313 are formed in both sides of the rocker 311 which each hold anoperating pin 314 which, when the coupling mechanism 300 is in acondition mounted ready to be operated, extend through a gate window 331of a locking element 330 which is supported via a locking elementsupport pin 332 in the coupling mechanism main body 320 and biased by aleg spring 338 in a clockwise direction, the term clockwise being basedon the plane of depiction of FIGS. 24 to 26 .

The locking element 330 is moveably supported in the coupling mechanismmain body 320. In a locked position it allows locking in apositive-locking manner in which the auxiliary drive device 100 iscoupled to the wheelchair 500 and the locking element 330 can be broughtin a release position by operating the handle 310 in which releaseposition uncoupling of the auxiliary drive device 100 from thewheelchair 500 is possible. The locking element 330 is formed such thatit can, in a spring loaded manner, in the embodiment as shown via theleg spring 338, close the coupling groove 321 completely or at leastpartially. In other words, in the locked position the locking elementprevents that a coupling pin 381 inserted into the coupling groove 321can move out of the coupling groove 321.

FIG. 28 , in connection with FIG. 27 , shows the symmetrical structureof the coupling mechanism 300 having two locking elements 330 and,correspondingly, two leg springs 338. Basically, provision of onelocking element 330 and one leg spring 338 is sufficient. The redundantembodiment having two locking elements 330 and two corresponding legsprings 338 shown in the figures provides single fault safety.

Coupling Mechanism (Coupling and Uncoupling)

The functions and the interaction as well as details of the design ofrespective elements of an embodiment of the coupling mechanism 300 areexplained in the following in connection with the process of couplingand uncoupling of an embodiment of an auxiliary drive device 100 to andfrom a wheelchair 500.

First, a coupling clamp 380 is attached at an axis 501 of a wheelchair500, preferably in the center between both rear wheels, or, if thewheelchair 500 does not have such an axis 501, for instance because itis a so-called folding wheelchair having a lateral folding mechanismhaving cross struts, at a corresponding accessory axis (not shown) whichis provided for this purpose and can be mounted to the wheelchair. Themounting of the coupling clamp 380 can be achieved for instance by aclamp mechanism.

The height of the coupling pin or, in case of a redundant design havingtwo coupling pins 381, of the coupling pins which these pins have abovethe road or the ground, that is the vertical distance of the pin or thepins with respect to the plane on which the wheels of the wheelchair 500stand, is of particular relevance. This height has an impact on thedriving geometry of the auxiliary drive device 100 and, accordingly, onthe drivability, especially concerning the position of the steeringshaft 130 which in an ideal case should be vertical with respect to thesurface on which the wheelchair stands. A particular influenceconcerning this height has the diameter of the rear wheels 502R, 502L ofthe wheelchair which in trade typically is for instance 24″ or 25″ andwhich, specifically depending on the chosen tires, leads to an effectivediameter of the wheel from 595 mm to 620 mm or 620 mm to 645 mm,respectively. A further major factor in this respect is the position atwhich the accessory axis (not shown) is attached to the wheelchair.

Naturally, a person skilled in the art has several options for providingsuch adjustment. In one exemplary embodiment, adjustment can be providedby means of various steering forks 131 in different length. However, inorder to reduce the number of different versions, in one embodiment afork can be provided with two or more bores or a slotted fork can beprovided, i.e. a fork having an elongated hole in which a so calledflip-chip can be inserted which allows two or more different attachmentheights. Furthermore, different versions of the coupling clamp 380 canbe provided in order to address varying heights of the attachment andthe proper height of the coupling pin 381 can be set and checked byusing a caliber or gauge.

When a coupling clamp 380 is attached at the wheelchair 500 and thecoupling pin 381 or the coupling pins 381 are adjusted in the properheight, the wheelchair 500 is ready for coupling of the auxiliary drivedevice 100. Firstly, the coupling mechanism of the auxiliary drivedevice 100 is in the coupling ready position as shown in FIG. 24 . Inthis coupling ready positon, the locking element 330, biased by theforce of the leg spring 338 and limited by the abutment of the operatingpin 314 in an angle of the gate window 331 correspondingly formed forthis purpose, takes an end position with respect to pivoting around thecenter axis of the locking element support pin 332 in a clockwisedirection, based on the drawing plane in the depictions according toFIGS. 24 to 26 , which plane is also the indication of direction for thefollowing description.

In this coupling ready position, no further rotation or pivotal movementof the locking element 330 can be effected by operation of the handle310. Accordingly, the handle 310 in so far assumes a firm position withrespect to the auxiliary drive device main body 120 which allows thatthe auxiliary drive device 100 can be lifted and carried by using thehandle 310 in order to place it over the coupling pin 381 so that, whenthe auxiliary drive device 100 is lowered, the coupling pin 381 entersinto the coupling groove 321 and rotates the locking element 330 bycontact at a first locking element contact surface 333 against thespring force of the leg spring 338 in a counter clockwise directionaround the center axis of the locking element support pin 332. Thisrotation is made possible by a corresponding design of the gate window331.

When the coupling pin 381 has completely entered into the couplinggroove 321, the coupling pin 381 has come into contact with acorrespondingly formed button of the coupling groove 321 and herebypartly releases the locking element 330 so that the locking element 330,due to the spring force of the leg spring 338, is rotated in a clockwisedirection around the center axis of the locking element support pin 332to an extent that a second locking element contact surface 334 gets incontact with the coupling pin 381. This rotation is made possible by acorresponding design of the gate window 331. Due to this, the couplingpin 381 is held in the coupling groove 321 in a positive-locking mannerand the auxiliary drive device 100 is ready to be operated and safelycoupled to the wheelchair 500 in the locked operation position of thecoupling mechanism 300 as shown in FIG. 25 while tilting or tipping ofthe wheelchair 500 is still possible.

The locking element 330 is designed such that during the couplingprocess, namely when this process is successfully terminated, itstrikes, in a spring-biased manner, an element which is to be held in apositive-locking manner for effecting the coupling. In one embodiment,the element to be held in a positive-locking manner for effecting thecoupling is the coupling pin 381. This strike produces a metallic sound.

In the embodiment as described here, this principle striking is realizedin that after release of the locking element 330, when the coupling pin381 has passed the first locking element contact surface 333, thelocking element 330 flips back under the effect of the leg spring 338until it strikes on the second locking element contact surface 334 ofthe coupling pin 381 whereby a metallic sound is produced in the form ofa click or clack in a simple way, specifically without providingadditional structural elements. This metallic sound is an acousticfeedback for the full, complete and safe coupling process. This is ofparticular advantage in cases where the coupling process is executed bya person sitting in the wheelchair who, from this position, can conductan optical check regarding the coupling only with great difficulty ornot at all.

The interaction of the leg spring 338, the locking element 330 and itsgeometric design, specifically with respect to the point of rotationaround the center axis of the locking element support pin 332, the gatewindow 331 and the two locking element contact surfaces 333 and 334 aswell as the coupling groove 321 allow a safe, secure and backlash-freethree point support of the coupling pins 381 which also is able tocompensate tolerances and wear. Particularly in connection with a drivesystem having a freely pivotable drive wheel 110, a backlash-freeconnection of the auxiliary drive device 100 and the wheelchair 500 isof particular importance.

A tendency of the coupling pin 381 to move downwards, that is in thedirection to the aperture of the V-shaped coupling groove 321 due to thespecific geometric design, specifically the shape and orientation of thesecond locking element contact surface 334 with respect to the shape ofa coupling groove 321 and the position of the point of rotation of thelocking element 330 around the center axis of the locking elementsupport pin 332, has the effect that the torque of the locking element330 around the center axis of the locking element support pin 332 in aclockwise direction is increased and the clamping force is also furtherincreased. This further enhances safety against unintended uncoupling.

An intended uncoupling of the auxiliary drive device 100 from thewheelchair 500 conducted by an operating person is effected in that thehandle 310 of the coupling mechanism 300 is pulled upward and, by doingso, it is rotated in a clockwise direction, together with the rocker311, around the center axis of the rocker support pin 312. This has theeffect that the operating pin 314, due to respective engagement in thecorrespondingly designed gate window 331 of the locking element 330,rotates the locking element 330 around the center axis of the lockingelements support pin 332 in an anti-clockwise direction so that thecoupling groove 321 is unblocked.

In the release position shown in FIG. 26 , the auxiliary drive devicecan be lifted by means of the handle 310 and uncoupled from thewheelchair 500. The direction in which power has to be exerted forunlocking the lock and lifting the auxiliary drive device 100 foruncoupling it from the wheelchair 500 by means of the handle 310 arepractically identical so that the unlocking and uncoupling process canbe easily and smoothly effected by one simple move of the hand. In otherwords, the operation of the handle 310 which moves the locking element330 in the unlocking position has the same direction of force ascarrying the auxiliary drive device 100 by means of the handle 310.

Upon releasing the handle 310, this and the locking element 330, due tothe force of the leg spring 338, return to the coupling ready positionaccording to FIG. 24 .

Adaption and Adjustment of the Operating Satellite

In connection with the explanation of the structure and the functions ofthe operating satellite 200, specific features including the adjustableratchet sensitivity have already been addressed. Further explanation isgiven in the following.

The ratchet upon rotating the rotational control ring 203 provides anaudible ratchet sound and a tactile feedback via the hand of theoperating person by means of a correspondingly selected encoder like,for example, an encoder type E33, provided by the company ELMA.

As far as software is concerned, the sensitivity of the ratchet distanceof the rotation control ring 203, i.e. the interrelation between oneincrement of turning and the effect on the speed, can be individuallyset via an end terminal like a smart phone or a PC, namely by asmartphone app or a PC service application. This makes it possible toaddress the needs of various user groups as well as their level ofhandicap. For instance, it can be desirable to provide only a very smallchange in speed in spite of a considerably large distance of themovement of operation. This is of considerable advantage for usershaving limited coordination ability of their arms and hands since themovements then can be executed in a gross motor manner.

On the other hand, in case of good fine motor skills and forwell-trained users, it can be of advantage if already a movement over asmall distance leads to a comparatively great change of the speed. Thisis particularly useful when driving outdoors where it may be intended toobtain the top speed quickly.

Exemplary values for a the effect of “ratchet” (or a click), i.e. adistinct increment of rotation, can be taken from table 1 below.

Change of speed per ratchet Set sensitivity: 0.1 km/h low 0.2 km/h 0.3km/h 0.4 km/h 0.5 km/h 0.6 km/h 0.7 km/h 0.8 km/h 0.9 km/h high 1.0 km/h

FIG. 29 shows a display of a smartphone arranged for setting andadjusting the sensitivity of the rotational control ring 203 of theoperating satellite 200. The sensitivity can be set between low and highby means of an electronic sliding controller.

Setting of the Automatic Adaption of the Cornering Speed

As already explained in connection with the description of the structureof an embodiment of an auxiliary drive device 100, a sensor can beadapted at the steering shaft 130 of the auxiliary drive device 100which sensor permanently monitors the steering angle of the drive wheel110.

In such case, a setting can be made as from which angle on the drivepower shall be reduced or increased. In one embodiment, this can be donefor instance via a computer program or a smartphone app. By reducing thedrive power in tight curves, controllability and ultimately the safetywill be increased because the cornering speed will be automaticallyreduced. Specifically, those wheelchair drivers having a higher spinalparalysis and limited function of the hands and fingers therefore gainadditional control concerning the drive.

In a narrow environment like for instance indoors, where for instancefurniture or other objects must be avoided, or while driving in heavilyfrequented pedestrian zones as well as generally in narrow curves,monitoring the steering angle is an additional safety feature becausethe drive power is appropriately reduced. When the steering anglebecomes smaller again and finally becomes zero, i.e. a straight drive,the drive power is increased correspondingly.

In a further embodiment, as a specific safety feature, the drive may becompletely switched off as soon as a critical steering angle is reached,for instance in case a steering angle is larger than 55° to the leftside or the right side which gives, in this example, a total rotationalrange of 110°.

In order to effect such a programming concerning the drivecharacteristics, the auxiliary drive device 100 is coupled with arespective end terminal, for instance a personal computer or smartphone,by use of a Bluetooth module. On this computer or smartphone, arespective software application for this additional drive features hasbeen installed. In one embodiment, a computer can be connected with theauxiliary drive device 100 via a cable, for instance a USB cable, andprogramming can be effected via cable connection.

FIG. 30 shows, in an exemplary depiction, a display of a smartphonearranged for setting the automatic adaption of the cornering speeddepending on a steering angle of the drive wheel 110. Monitoring of theangle can be completely switched off or can be set up to a maximum valueof for instance 110° by use of an electronic slide controller.

It is understood that also other settings and switching on or offoperations can be effected by such an external device, for instanceswitching ON and OFF of the rear light 122. Furthermore, such an app candisplay operational parameters like for instance the state of charge ofthe main battery 121 or of the operating satellite battery on thesmartphone.

The control functions of the described embodiments make use ofelectronic control elements, wherein respective components are arrangedin particular in the operating satellite 200, in the auxiliary drivedevice main body 120 and in the drive wheel 110.

The control functions can be implemented by circuitry including at leastone semiconductor integrated circuit such as at least one processor(e.g., a central processing unit (CPU)), at least one applicationspecific integrated circuit (ASIC), and/or at least one fieldprogrammable gate array (FPGA). At least one processor is configurable,by reading instructions from at least one machine readablenon-transitory tangible medium, to perform all or a part of the controlfunctions. Such a medium may take many forms, including, but not limitedto, any type of magnetic medium such as a hard disk, any type of opticalmedium such as a CD and a DVD, any type of semiconductor memory (i.e.,semiconductor circuit) such as a volatile memory and a non-volatilememory. The volatile memory may include a DRAM and a SRAM, and thenonvolatile memory may include a ROM and a NVRAM. The ASIC is anintegrated circuit (IC) customized to perform, and the FPGA is anintegrated circuit designed to be configured after manufacturing inorder to perform, all or a part of the control functions.

Although some example embodiments of the technology are describedhereinabove, the foregoing example embodiments are mere examples and arenot intended to limit the scope of the technology. It should beappreciated that modifications and alterations of the foregoing exampleembodiments may be made. It should be also appreciated that variousomissions, replacements, and modifications may be made in the foregoingexample embodiments described herein, without departing from the scopeof the spirit of the technology. The technology is intended to includesuch modifications and alterations in so far as they fall within thescope of the appended claims or the equivalents thereof.

List of reference signs - 100 auxilliary drive device 105 steering shaftrotational angle sensor 110 drive wheel 111 motor 112 tire surface 113tire surface bolts 118 slip ring 120 auxilliary drive device main body121 main battery 122 rear light 123 main switch 124 main body chargingsocket 130 steering shaft 131 steering fork 132 stop gliding element -guiding element 133 elongated hole 134 stop gliding element 135 stopelement 135A first side of stop element 135 135B second side of stopelement 135 200 operating satellite 201 undercut 202 operating satellitecontrol portion 203 rotational control ring 204 push control knob 205display device 205A LED element white 205B LED element RGB 206 coverelement 207 fixing screw 208 grip link 209 unlocking element 210operating satellite mounting element 211 locking hook 218 adaptercharging socket 219 pairing button 220 operating satellite mountingpivot element 221 latches 221A latch bar 222 fixing hook 223 releasebutton 224 push rod 225 pressure spring 226 reverse lever 230 wheelchairmounting element 231 mounting bolt 300 coupling mechanism 310 handle 311rocker 312 rocker support pin 313 operating pin receiving bore 314operating pin 320 coupling mechanism main body 321 coupling groove 330locking element 331 gate window 332 locking element support pin 333first locking element contact surface 334 second locking element contactsurface 338 leg spring 380 coupling clamp 381 coupling pin 500wheelchair 501 axis 502L left rear wheel 502R right rear wheel 504pushrim 505 front wheel

1. An auxiliary drive device for a wheelchair, comprising: at least oneelectrically driven drive wheel; a coupling mechanism for coupling theauxiliary drive device to a wheelchair; and a steering shaft on whichthe electrically driven drive wheel is supported, wherein theelectrically driven drive wheel is freely pivotable with respect to theauxiliary drive device, and wherein the steering shaft is arranged suchthat, when the auxiliary drive device is coupled to the wheelchair readyto be operated, a castor is provided for the electrically driven drivewheel.
 2. The auxiliary drive device according to claim 1, wherein drivefunctions of the electrically driven drive wheel can be controlled viaan operating satellite which can be attached to the wheelchair whereinthe operating satellite preferably has a push control knob forcontrolling specifically ON and OFF functions and a rotational controlring for initiating drive and selection of a driving speed.
 3. Theauxiliary drive device according to claim 1, further comprising ahandle, wherein the coupling mechanism includes a movable lockingelement which is movably supported in the coupling mechanism, whereinthe movable locking element can be in a locking position in which itcauses locking in a positive-locking manner so that the auxiliary drivedevice is coupled to the wheelchair, wherein the locking element, byoperation of the handle, can be moved in a release position in whichuncoupling of the auxiliary drive device from the wheelchair ispossible, wherein the locking element is spring loaded, such that thelocking element can close a coupling groove completely or at leastpartially and, in the process of coupling the locking element contactsin a spring loaded manner an element to be held in a positive-lockingmanner to effect the coupling, wherein the coupling groove is arranged,with respect to the handle such that, when the auxiliary drive device isheld by the handle, the coupling process is carried out by lowering theauxiliary drive device, wherein the element to be held in apositive-locking manner for effecting the coupling comprises a couplingpin and enters, due to the lowering, into the coupling groove and thecoupling process is completed when the coupling pin to be held in apositive-locking manner for effecting the coupling has come in abutmentwith a corresponding bottom of the coupling groove, and wherein thecoupling pin and the coupling groove are designed such that, in case ofa coupling of the auxiliary drive device with the wheelchair, safe tooperate a tilting of the wheelchair with respect to the auxiliary drivedevice is possible.
 4. The auxiliary drive device according to claim 3,wherein the handle is adapted to carry the auxiliary drive device. 5.The auxiliary drive device according to claim 1, further comprising: atleast one sensor by which driving of a curve can be detected; and anelectronic control unit for controlling functions of the auxiliary drivedevice, wherein the electronic control unit is adapted to influence adriving speed depending on a radius of the curve.